Murder on the Orient Express Foreignness and 'the Other' Quotes

How we cite our quotes: (Part.Chapter.Paragraph)

Quote #4

"No," said Mr. Bouc thoughtfully. "This is the act of a man driven almost crazy with a frenzied hate – it suggests more that Latin temperament. Or else it suggests, as our friend the chef de train insisted, a woman." (1.6.128)

Mr. Bouc suggests that only someone of the "Latin temperament" could have committed the crime – or a woman. What is the significance of this connection?